One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

Named after a legendary garden called Eram in southern Arabia, built by order of Shaddad, an Arab king who wanted to compete with Paradise.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

This massive library holds what was once the largest book collection in the world.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

The celebrated eyesore created by starry-eyed sweethearts.

In Florence's great Duomo, a 26 foot fresco honors a mercenary famous for attacking Florence.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.

Mysterious standing stone formations looks like a petrified forest.

This historic black and white monastery is one of Bulgaria's architectural jewels.

"Holy Wisdom" overlooks the city that became its namesake.

A striking symbol of the Bulgarian capital.

Rock carving created 1,300 years ago 75 feet off the ground.

An ancient Thracian city where fire rituals were practiced on the largest cult altar in Southeast Europe.

In a long-dry lake bed, these groups of massive stone pillars bear a striking resemblance to clumps of everyone's favorite fungi.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

An homage to the medieval rulers of Bulgaria.

UNESCO-protected ancient burial ground.

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.